A rudimentary path tracer that can be compiled to run on the Game Boy Advance.
The renderer performs rather poorly on the GBA's limited hardware. An image like the one below (240 x 160 pixels) might take a day or more to render. But it does render.
Script files are provided for building slowray for both the GBA and PC.
You will need DevKit Advance to build slowray for the GBA; although other such toolsets may also work.
When building for the GBA, globally define
SLOWRAY_ON_GBA. When building for the PC, globally define
SLOWRAY_ON_PC. The script files noted above take care of this automatically.